Bending apparatus

ABSTRACT

APPARATUS FOR MAKING A PRODUCT, SUCH AS AN EXPANSION SHELL, FROM A STRIP OR METAL INCLUDES A STATION FOR SHEARING NOTCHES ALONG ONE SIDE OF THE STRIP TO FORM THE LEAVES OF A SHELL AND A STATION TO SHEAR A BLANK, INCLUDING A NUMBER OF THE LEAVES, FROM THE STRIP AND TO BEND THE BLANK ABOUT A MANDREL BY MEANS OF A PAIR OF PIVOTALLY MOUNTED DIES.

Nov. 23, NH c. W. SCHAEFFER BENDI NU APPARATUS 2 Sheets-Sheet 1 FiledJune 17, 1969 35 INVENTOR Char/es 1/14 Sc/raef/Er United States Patent3,621,704 BENDING APPARATUS Charles W. Schaeifer, Lebanon, Pa., assignorto Bethlehem Steel Corporation Filed June 17, 1969, Ser. No. 834,003Int. Cl. B21d 9/05, 28/00 U.S. Cl. 72-339 Claims ABSTRACT OF THEDISCLOSURE BACKGROUND OF THE INVENTION This invention relates generallyto an apparatus for making a product from a strip of metal and morespecifically to apparatus which shears a blank from the strip and bendsthe blank about a mandrel.

Heretofore, products, such as the mine roof expansion shell disclosed inU.S. Pat. No. 3,000,254 to Hottenstein, were made by casting metal intoa mold. The products so made are relatively expensive. While someproducts, such as the tubular articles disclosed in U.S. Pat. No.2,126,473 to Keller, were made by shearing a blank from a strip of metaland bending the blank about a mandrel, the bending operation wasrelatively inefiicient and expensive due to the complexity of thebending dies and the number of bending steps required to arrive at thefinished product.

SUMMARY OF THE INVENTION An object of this invention is to provideapparatus capable of efficiently and inexpensively making a product,such as an expansion shell.

This object can be attained by providing an apparatus which feeds astrip of metal to an arrangement of dies which successively shears aplurality of notches along one side of the strip, cuts a blank from thestrip and bends the blank about a mandrel. The bending step isaccomplished by a pair of pivotally mounted dies which force the blankto conform to the shape of the mandrel.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectionalview of the apparatus of this invention.

FIG. 2 is a sectional view taken along the line 22 of FIG. 1.

FIG. 3 is a sectional view taken along the line 33 of FIG. 1.

FIGS. 4, 5 and 6 are sectional views showing successive steps in theoperation of the cutoff and bending station dies.

FIG. 7 is a plan View of the strip at the various stations.

FIG. 8 is a sectional view taken along the line 8-8 of FIG. 7.

FIG. 9 is a view taken along the line 99 of FIG. 7.

DETAILED DESCRIPTION OF THE DRAWINGS The apparatus of this invention isarranged as a threestation die set. With particular reference to FIG. 1,the first station is generally indicated as 10, the second station as11, and the third station as 12. The die set is of a type well known inthe art with the lower tools fixed to the bed plate of a vertical pressby means of a lower mounting plate 13, and the upper tools fixed to themovable 3,621,704 Patented Nov. 23, 1971 member of the press by means ofan upper mounting plate 14. Thus, the upper mounting plate 14 and thetools attached thereto are movable toward and away from the lowermounting plate 13 and its tools. A strip of metal is fed between theupper and lower tools along the line 16. The lower tools support thestri and the upper tools cooperate with the lower tools to make thedesired product.

While the die set of this invention is described as mounted on avertical press with the upper mounting plate 14 movable with respect tothe lower mounting plate 13, it is obvious that the die set could bemounted on any type press and that the lower mounting plate 13 could beadapted to move relative to the upper mounting plate 14.

U.S. Pat. No. 1,632,462 to Candee discloses a power press which could beused to produce the desired movement between the upper and lower tools.To the extent that the means to produce such movement is necessary for acomplete disclosure of this invention, the disclosure of the abovepatent to Candee is hereby incorporated by reference.

FIG. 1 shows the die set in the closed position, i.e., the upper toolshave moved downwardly to their lowest position. Line 16 indicates theapproximate centerline of the strip 15 as it is fed between the tools.Rollers 17 intermittently feed the strip 15 between the tools along line16 in a manner well known in the art. In addition guides 18 aid inproperly positioning the strip 15 with respect to the tools.

As shown in FIG. 8, the strip 15 of metal has a transverse cross sectionsimilar to the cross section of a leave 4 shown in FIG. 2 of the abovepatent to Hottenstein. However, this cross sectional shape is by way ofillustration and this invention may be applied to other cross sectionalshapes depending on the desired product.

FIRST STATION Referring to FIGS. 1 and 7, the first station tools sheara plurality of notches 19 along one side of the strip 15 and thus formsfour leaves 20 of an expansion shell. The upper tools include four shearknives 21 which are mounted in a holder 22 which bears against liner 23and is secured to the upper mounting plate 14. The lower tools include alower die 24 having four openings 25 therein and secured to lowermounting plate 13. The openings 25 of die 24 are in vertical alignmentwith openings 68 in lower mounting plate 13. Each knife 21 is verticallyaligned with an opening 25. The shape of each opening conforms to theshape of a knife 21 which is shaped to produce the keyhole shaped notch19. A stripper plate 26 is secured to lower die 24 and acts to free thestrip 15 of metal from the knives 21 after notches 19 have been made inthe strip 15. Since stripper plates are well known in the art, furtherdescription of the stripper plate 26 appears unnecessary.

SECOND STATION Referring to FIGS. 1, 3, 7 and 9, the second stationtools contact the leaves 20 formed in the first station and formchamfers 27 along the edges of the serrated portions 28 of the leaves20. The upper tools include a forming die 29 mounted in die holder 30and secured to the upper mounting plate 14. A liner 3.2 is positionedbetween the upper mounting plate 14 and the forming die 29 and dieholder 30. The face 33 of the forming die 29 is serrated to conform tothe serrated portion 28 of the strip 15, and also arcuate to produce thechamfers 27 on the leaves 20. The lower tools include a die 34 and astrip guide 25 secured to die 34 by a bolt 36 which passes through ahole in the guide 35 and is in threaded engagement with a tapped hole inthe die 34. The edge of strip 15 engages the edge 37 of guide 35. Spring38 allows the guide 35 to adjust to minor irregularities in the width ofthe strip 15.

Obviously, the above first and/ or second station tooling could beomitted if the product to be made does not require such tooling.

THIRD STATION The third station tools shear a blank 39, FIG. from thestrip 15 and bend the blank 39 about a mandrel 40. As best shown in FIG.1, the upper tools include die holder 41 which is positioned against aliner 42 and secured to the upper mounting plate 1 4, a pair of verticalmembers 43 which are secured to the ends of die holder 41, and a pair ofdies 44, 44 pivotally attached to the die holder 41. Each die 44 ispivotally attached to the die holder 41 by means of a pin 45 whichpasses through a hole in the die 44 and a similar hole in an integralclevis portion 46 of the die holder 41.

Referring to FIGS. 1 and 2, the lower tools include stop 67, mandrel 40,mandrel support member 47 and means to eject a bent blank from themandrel 40. The stop 67 is attached to lower mounting plate 13. Themandrel support member 47 is attached to the lower mounting plate 13,and the mandrel 40- has an integral shank portion 48 attached to thesupport member 47. Mandrel 40 extends above an opening 69 in lowermounting plate 13-. The means to eject a bent blank from the mandrel 40includes four pins 49 which extend through holes in the support member47 adjacent the outer surface of the mandrel 40. A compression spring'50 which surrounds each pin 49 urges the pin 49 and the piston 51,which is slidably mounted within a cylindrical opening 52 in supportmember 47, to the left as viewed in FIG. 2. Each spring 50' has one endin contact with the support member 47 and the other end in contact withthe head of a pin 49. An O-ring 65 fixed to piston 51 seals the spacebetween the piston 51 and the inner surface of the cylindrical opening52. Attached to the end of the support member 47 opposite the mandrel 40is a fitting 53 which includes a passageway 66 for the admission of airpressure to force the piston 51 and pins 49 to the right. In so moving,the pins 49 contact a blank which is bent about the mandrel 40 and ejectthe bent blank from the mandrel 40. After the air pressure has beenremoved springs 50 cause the piston 51 and pins 49 to return to theposition shown in FIG. 2.

As shown in FIG. 4, pins 45, 45 which pivotally mount dies 44, 44 to thedie holder 41, extend parallel to a plane which includes the line 54,extends perpendicular to the longitudinal centerline of the strip 15,and passes through the longitudinal axis 55 of the mandrel 40, alsoshown in FIG. 2. In addition, the pins 45 are displaced on oppositesides of this plane. Each die 44 includes a vertically extending leg 56and a horizontally extending leg 57. The weight of each die 44 isdistributed so that the die 44 naturally assumes the position shown inFIG. 4. The relative positions between the horizontal leg 57, verticalleg 56 and the pin 45 of each die 44 is such that an upward force on thevertical leg 56 indicated by arrows SSL and 58R, for the left and rightdie 44 respectively, will tend to rotate the die in the directionindicated by arrows 59L and 59R, while an upward force on the horizontalleg 57 indicated by arrows 60L and 60R, for the left and right die 44respectively, will rotate the die in the direction indicated by arrows61L and 61R. As to rotation in the direction indicated by arrows 59L and59R, it Can be seen that vertical members 43 act as stops and preventsuch a rotation of the dies.

As the die holder 41 moves from the position shown in FIG. 4 to that ofFIG. 5, the right vertical member 43 cooperating with the edge 68 of die34 shears a blank 39 from the strip 15. In addition, the verticalmembers 43 and the vertical legs 56 of the dies 44 cause the blank 39 tobe bent about the upper two sides of the mandrel 40. It can also be seenthat a working face of each die,

i.e. the surface of each die 44 which comes in contact with the blank 39and indicated by numeral 62, can no longer have straight line verticalmovement because a portion 63 of the horizontal leg 57 working face isin contact with a portion of the blank 39 which has been bent about themandrel 40. Thus, as the die holder 41 moves from the position shown inFIG. 5 to the position shown in FIG. 6, the dies 44 rotate in thedirection of arrows 61L and 61R for the left and right die 44,respectively, because of the reaction between the stationary mandrel 40and the working face on the horizontal leg 57. In so rotating, thevertical leg 56 wraps the blank 39 completely about the mandrel 40- toform an expansion shell 70.

SEQUENCE OF OPERATION During the following sequence of operation, thelower mounting plate 13 and its tools remain stationary, and the uppermounting plate 14 moves between a first position (hereinafter referredto as position A), Le. the upper mounting plate 14 is raised so that thelower ends of the shear knives 21 are above the strip 15 and the toolsof the third station are positioned as shown in FIG. 4, and a secondposition (hereinafter referred to as position B), i.e. the uppermounting plate and its tools are positioned as shown in FIG. 1.

First step. A strip 15 of metal is fed by rollers 17 to the firststation 10- while the upper mounting plate 14 is in position A. Theupper mounting plate 14 is then moved to position 1B and in so doingknives 21 cooperate with openings 25 in lower die 24 to shear fournotches 19 along one side of strip 15. The upper mounting plate is thenreturned to position A.

Second step. Rollers '17 feed the strip 15 into the second station 11.The upper mounting plate is then moved to position B. During thismovement, four additional notches are sheared in the strip at the firststation 10 as described above. In addition, the forming die 29 and die34 of the second station 11 cooperate to form chamfers 27 on theserrated portion 28 of the leaves 20 formed in the first station 10. Theupper mounting plate 14 is then moved to position A.

Third step. Rollers 17 feed the strip 15 into the third station 12 untilthe end of the strip contacts stop 67. The upper mounting plate 14 isthen moved to position B. During this movement, the tools of the firststation 10 and second station 11 performed the shearing and formingsteps described above. In addition, the right vertical member 43cooperates with edge 68 of second station lower die 34 to shear a blank39 including four leaves 20 from the strip 15. The vertical members 43and vertical legs 56 of dies 44 bend blank 39 about the upper two sidesof the mandrel 40'. The working face 62 of horizontal legs 57 of dies 44come in contact with the strip 15 which is bent about the mandrel 40.The dies 44 rotate in the direction of arrows 61L and 61R and theworking face of the vertical leg 56 completes the bending of the blank39 about the lower two sides of the mandrel 40 to form an expansionshell 70. The upper mounting plate is then moved to position A. Airpressure is then supplied through passageway 66 of fitting 5-3 tocylindrical opening 52. Thereupon piston 51 moves pins 49 to the rightfrom the position shown in FIG. 2 and the formed shell 70 is ejectedfrom the mandrel 40. Pressure is then removed from. the piston 51, andsprings 50 forces pins 49 and piston 51 to the position shown in FIG. 2.Thereafter, the above third step is repeated.

While the above description is directed to an expansion shell havingfour leaves and bent around a square mandrel, this invention can be usedto make shells having any number of leaves and to bend blanks around amandrel having other than a square shape. In addition, as stated abovethis invention can be used to make products other than expansion shells.

I claim: 1. Apparatus for bending a strip of metal comprising: (a) amandrel in contact with one side of said strip intermediate the endsthereof,

(3) means to bend said blanks into an expansion shell comprising:

(a) a mandrel in contact with one side of said blank intermediate theends thereof,

(b) a die holder disposed adjacent the other side of 5 (b) a die holderdisposed adjacent the other said strip, side of said blank,

(c) a pair of dies pivotally mounted in said die holder (c) a pair ofdies pivotally mounted in said between a pair of vertically extendingmembers atdie holder, each of said pair of dies havtached to said dieholder, each of said pair of dies ing a Working face, the pivotal axesof said having a substantially vertically extending leg arpair of diesextending parallel to and disranged to contact a vertically extendingmember and placed on opposite sides of a plane suba substantiallyhorizontally extending leg the pivotal stantially perpendicular to saidstrip and axes of said pair of dies extending parallel to and passingthrough the longitudinal axis of displaced on opposite sides of a planesubstantially said mandrel, perpendicular to said strip and passingthrough the 1 (d) means for moving the die holder tolongitudinal axis ofsaid mandrel, ward and away from said mandrel, and

(d) means for moving the die holder toward and (e) the location of theaxes and the workaway from said mandrel, and ing faces of said pair ofdies being such (e) the location of the axes and said legs of said pairthat on movement of the die holder toof dies being such that on movementof the die ward the mandrel said pair of dies contact holder toward themandrel said vertically extendsaid blank to bend said blank about a ingmembers and said vertically extending legs of portion of said mandreland further movesaid pair of dies contact said strip to bend said stripment of the die holder toward the mandrel about a portion of saidmandrel and upon further causes said pair of dies to rotate on theirmovement of the die holder toward the mandrel, axes solely by reactionbetween the mansaid horizontally extending legs of said pair of diescontact said strip causing said pair of dies to rotate on their axessolely by reaction between the mandrel and said horizontally extendinglegs of said pair of dies to further bend said strip about said mandrel.

2. Apparatus of claim 1 wherein said mandrel has a substantially squaretransverse cross section and a diagonal of said square lies in saidplane.

3. Apparatus of claim 1 including means to eject the 5. The apparatus ofclaim 4 further comprising means to form a chamfer along a portion ofthe sheared edges of the notches.

References Cited UNITED STATES PATENTS bent strip from said mandrel. 32,477,910 8/ 1949 Tal 72383 4. Apparatus for making an expansion shellhaving a 2,437,810 1 9 Hunt 72-383 plurality of leaves comprising:2,497,622 /1950 Mueller 72-383 (a) means for feeding a strip of metalbetween opposed die means, (b) said die means including 1) means toshear a plurality of notches along one side of said strip to form theleaves of said shell, (2) means to shear a blank including a pluralityof leaves from said strip, and 45 CHARLES W. LANHAM, Primary Examiner R.M. ROGERS, Assistant Examiner US. Cl. X.R. 72383, 387

